1. Field of the Invention
The present invention relates to a method, system, and program for selecting a path comprising ports on primary and secondary clusters to use to transmit data at a primary volume to a secondary volume.
2. Description of the Related Art
Host systems in a storage network may communicate with a storage controller through multiple paths. The storage controller may be comprised of separate storage clusters, where each storage cluster is capable of accessing the storage and provide redundancy to access the storage. If a storage cluster fails, then the host may failover to using the other storage cluster to access the storage.
In certain system architectures, data written to primary volumes in a primary storage system may be mirrored at secondary volumes at a secondary storage system to assist with data recovery and data deployment. Such dual or shadow copies are typically made as the application system is writing new data to a primary storage device. International Business Machines Corporation (IBM) provides Extended Remote Copy (XRC) and Peer-to-Peer Remote Copy (PPRC) solutions for mirroring primary volumes at secondary volumes at separate sites. These systems provide a method for the continuous mirroring of data to a remote site to failover to during a failure at the primary site from which the data is being continuously mirrored. Such data mirroring systems can also provide an additional remote copy for non-recovery purposes, such as local access at a remote site. In such backup systems, data is maintained in volume pairs. A volume pair is comprised of a volume in a primary storage device and a corresponding volume in a secondary storage device that includes an identical copy of the data maintained in the primary volume.
A primary storage controller may maintain copy relationship information on primary and secondary volumes in a volume pair. The primary storage controller may manage the establishment of the initial copy of the primary volume at the secondary volume by transmitting the primary volume data to a secondary storage controller managing access to the secondary volume in the copy relationship. After the initial copy is established, then the primary storage controller transfers updates to the primary volume in the volume pair to the secondary volume.
There may be multiple paths between adapters in the primary storage controller, which may be on different primary clusters (processing complexes), and adapters in the secondary storage controller, which may also have multiple clusters. In certain systems, the primary storage controller may use load balancing to select a path to use to transfer data for a primary volume to the secondary storage controller to write to the secondary volume in the copy relationship.
There is a need in the art for improved techniques for selecting paths to use to transfer data between primary and secondary volumes in a copy relationship.